Kinematics And Trajectory Planning Of A Four-degree-of-freedom Underwater Manipulator

The deep-sea manipulator which is configured on the underwater robot is the core tool of the underwater robot system.Compared with the working environment for traditional industrial robots,the underwater manipulator needs to sneak into the seabed for work.The working environment is unknown,more complex and changeable compared to the on land environment.In order to cope with the complex and unknown working environment in the seabed,it is more important to study the kinematics,working space and trajectory planning of underwater manipulators.The kinematics research can reflect the maneuver performance of the manipulator.The workspace analysis can reflect the manipulator's working range.It is an important reference index when manipulating the manipulator.The trajectory planning provides a theoretical basis for the actual working process and control of the manipulator.This paper is a study of kinematics and trajectory planning for a four degree-of-freedom(DOF)underwater manipulator that developed independently.The main research contents of this paper are showed follows:Firstly,the four DOF underwater manipulator system studied in this paper is analyzed.The composition of the manipulator system and the function of each module are explained.The selection strategy of the driving mode of the underwater manipulator is discussed.And the D-H front reference coordinate system of the manipulator model is established,and the motion parameters between the joints of the manipulators are determined.Secondly,the positive kinematics model of the manipulator is solved based on the DH parameter method.The negative kinematics of the manipulator is solved by the traditional algebraic method,and the BP neural network algorithm is applied to solve the negative kinematics of the four-degree-of-freedom underwater manipulator.The BP neural network for solving the negative kinematics model is built.The reliability of the neural network for negative kinematics is verified.The kinematics model is validated based on the ADAMS virtual prototype.Thirdly,based on the Monte Carlo method,the horizontal working space,the pitch working space and the overall working space of the manipulator are solved respectively,and the Jacobian matrix of the four DOF underwater manipulator is calculated,and the end of the manipulator is.The flexibility of the actuator movement in the workspace was analyzed that based on the solution of the end actor's Jacobian matrix.Finally,the trajectory planning method of the underwater manipulator joint space is analyzed.The cubic spline planning algorithm is deduced and calculated.The application of the four DOF underwater manipulator in the deep sea microbial suspension culture equipment is analyzed.Taking this working process as an example,the trajectory planning scheme of the motion was developed by using the cubic spline algorithm,and the results were simulated and analyzed.The contents studied in this paper can verify the maneuverability of the manipulator and the rationality of the structure of the underwater manipulator,and provide a basis for further development of the control scheme of the underwater manipulator.